GEODESY I N AVI ATI ON, GEODESY I N AVI ATI ON, I mplementation of the WGS 84 I mplementation of the WGS 84 Datum for the Global Navigation Datum for the Global Navigation Satellite System Satellite System 2001 I nternational Symposium on 2001 I nternational Symposium on GPS/ GNSS GPS/ GNSS Fred Henstridge Fred Henstridge November 8, 2001 November 8, 2001 Jeju I sland, Korea Jeju I sland, Korea
P S O M A S PRESENTATI ON AGENDA PRESENTATI ON AGENDA � What is CFI T � What is CFI T � The I mportance of GNSS � The I mportance of GNSS � Datums � Datums � Purpose of WGS 84 Surveys � Purpose of WGS 84 Surveys � Typical Airfield Survey � Typical Airfield Survey � Quality Assurance � Quality Assurance � GI S for Airports � GI S for Airports � Discussions � Discussions November 8, 2001 Geodesy In Aviation Slide No. 2
P S O M A S CFI T- I t Does Not Have to Be CFI T- I t Does Not Have to Be � Controlled Flight I nto Terrain (CFI T)? � Controlled Flight I nto Terrain (CFI T)? � 33% of all Fatalities since 1985 � 33% of all Fatalities since 1985 � Guam, Aug. 6, 1997 228 Fatalities � Guam, Aug. 6, 1997 228 Fatalities � Van, Turkey, December 29, 1994 54 Fatalities � Van, Turkey, December 29, 1994 54 Fatalities � Philippines, Feb. 2, 1998 104 Fatalities � Philippines, Feb. 2, 1998 104 Fatalities � El Salvador, Aug. 8, 1995 65 Fatalities � El Salvador, Aug. 8, 1995 65 Fatalities � Buga, Colombia, Dec. 20, 1995 160 Fatalities � Buga, Colombia, Dec. 20, 1995 160 Fatalities � Arequipa, Peru, Feb. 29, 1996 123 Fatalities � Arequipa, Peru, Feb. 29, 1996 123 Fatalities � I ndonesia, Dec 19, 1997 97 Fatalities � I ndonesia, Dec 19, 1997 97 Fatalities � The List Goes On ........................... � The List Goes On ........................... November 8, 2001 Geodesy In Aviation Slide No. 3
P S O M A S The I mportance of GNSS The I mportance of GNSS � Satellite-based Navigation Offers Substantial � Satellite-based Navigation Offers Substantial Safety and Operating Benefits Vs. The Existing Safety and Operating Benefits Vs. The Existing Ground-based Navigation System Ground-based Navigation System � A Boeing Study Covering 1986 to 1996 � A Boeing Study Covering 1986 to 1996 Determined That Large Commercial Jets Have Determined That Large Commercial Jets Have Crashed in Latin America at a Rate of 4.5 Per Crashed in Latin America at a Rate of 4.5 Per Million Flights, Three Times the World Average Million Flights, Three Times the World Average and Nine Times the U.S. Average and Nine Times the U.S. Average � The Majority of CFI T Accidents Occur During � The Majority of CFI T Accidents Occur During the Final Descent, on Course but Short of the the Final Descent, on Course but Short of the Runway Runway November 8, 2001 Geodesy In Aviation Slide No. 4
P S O M A S Advantages to GNSS Advantages to GNSS � Safer � Safer � All Weather Functional � All Weather Functional • Can Land Aircraft in All Weather • Can Land Aircraft in All Weather s � Human Element Minimized � Human Element Minimized e � Collision And Flight I nto Terrain Avoidance v � Collision And Flight I nto Terrain Avoidance a s � More Accurate I nstrument Approach Procedures � More Accurate I nstrument Approach Procedures S e v � More Efficient Air Traffic Management � More Efficient Air Traffic Management i L � Saves Time � Saves Time • Increased Airport Acceptance Rates • Increased Airport Acceptance Rates � Saves Fuel � Saves Fuel • Increases Pay Loads • Increases Pay Loads • Less Costly • Less Costly � I ncreased Use of Airspace � I ncreased Use of Airspace November 8, 2001 Geodesy In Aviation Slide No. 5
P S O M A S GPS Navigation GPS Navigation Global Navigation Satellite System (GNSS) GNSS Route Ground Controlled Route November 8, 2001 Geodesy In Aviation Slide No. 6
P S O M A S Geodesy Geodesy � Describing the Earth � Describing the Earth � Shape of Earth (Big Potato) � Shape of Earth (Big Potato) � Definitions � Definitions � Spheroid or Ellipsoid � Spheroid or Ellipsoid � Datum � Datum � Geoid � Geoid • Gravity Field • Gravity Field • Mean Sea Level (MSL) • Mean Sea Level (MSL) � Visual Presentation (Maps and Charts) � Visual Presentation (Maps and Charts) • Coordinates • Coordinates • Projections • Projections November 8, 2001 Geodesy In Aviation Slide No. 7
P S O M A S Geodetic Datums Geodetic Datums � Numerous World-Wide � Numerous World-Wide Datums Datums � 280+ � 280+ � 100 Years Old � 100 Years Old � Best Fit for a Local Area � Best Fit for a Local Area (Country) (Country) � Used Mainly for Mapping � Used Mainly for Mapping � Not Suited for Global Data � Not Suited for Global Data I nterchange I nterchange November 8, 2001 Geodesy In Aviation Slide No. 8
P S O M A S Local Geodetic Datums Local Geodetic Datums � > 200 Datums in the World I n Use Today � > 200 Datums in the World I n Use Today � Scientific and Political Reasons � Scientific and Political Reasons � Much Disagreement � Much Disagreement � Scientific and Political Reasons � Scientific and Political Reasons � GPS Navigation Requires Agreement � GPS Navigation Requires Agreement � Common Ellipsoid and Height Reference (Horizontal � Common Ellipsoid and Height Reference (Horizontal and Vertical Datum) and Vertical Datum) � An Aircraft Leaving Point “A” and Flying to Point “B”, � An Aircraft Leaving Point “A” and Flying to Point “B”, With the Assistance of GNSS, Needs to Have Both With the Assistance of GNSS, Needs to Have Both Points “A” and “B” Related to the Same Datum I f a Points “A” and “B” Related to the Same Datum I f a Safe Arrival I s Expected. Safe Arrival I s Expected. • WGS-84 Is The Specified Datum by ICAO, The United Sates FAA • WGS-84 Is The Specified Datum by ICAO, The United Sates FAA and the DoD. and the DoD. November 8, 2001 Geodesy In Aviation Slide No. 9
P S O M A S Ellipsoid Ellipsoid � Mathematical Model of the Earth � Mathematical Model of the Earth � Have Become More Accurate � Have Become More Accurate � Great Variety � Great Variety � Mathematically Described by � Mathematically Described by � Semi Major axis (a) � Semi Major axis (a) � Semi Minor axis (b) � Semi Minor axis (b) � flattening (f), f= (a-b)/ a � flattening (f), f= (a-b)/ a � Eccentricity (e), e 2 = f * (2-f) � Eccentricity (e), e 2 = f * (2-f) November 8, 2001 Geodesy In Aviation Slide No. 10
Slide No. 11 SEMI-MAJOR AXIS Typical Ellipsoid Model a b SEMI-MINOR AXIS Geodesy In Aviation Flattening November 8, 2001 P S O M A S
Slide No. 12 Geoid Geodesy In Aviation Ellipsoids Ellipsoids Ellipsoids November 8, 2001 P S O M A S
P S O M A S Ellipsoidal Shifts Ellipsoidal Shifts Local Ellipsoid Global Ellipsoid WGS 84 Geoid (Orthometric Height) November 8, 2001 Geodesy In Aviation Slide No. 13
P S O M A S WGS 84 Ellipsoid WGS 84 Ellipsoid Ellipsoidal Parameters Semi-Minor Axis = Polar Radius = b (WGS- 84 value = 6356752.3142 meters) Semi-Major Axis = Equatorial Radius = a (WGS- 84 value = 6378137.0 meters) Flattening = f = (a-b)/a (WGS- 84 value = 1/298.257223563) First Eccentricity Squared = e ∧ 2 = 2f-f ∧ 2 (WGS- 84 value = 0.00669437999013) November 8, 2001 Geodesy In Aviation Slide No. 14
P S O M A S Example of Datum Shifts Example of Datum Shifts 97° 44’25.19” West WGS 84 Cape European Datum 1950 There Are Over 280 There Are Over 280 Active Mapping Datums Active Mapping Datums South American 1969 In The World Today In The World Today 30° 16' 28.82” North WGS 84 British Ordinance Survey 1936 Australian Geodetic System 1984 500 Meters Tokyo Indian 1000 Meters November 8, 2001 Geodesy In Aviation Slide No. 15
P S O M A S Effect of Datum on Aviation Effect of Datum on Aviation Where the end of the runway is located based on Local 36 Datum Where the aircraft is at the end of the GPS approach procedure 462 m using WGS-84 Datum 245 m The Position of the Runway Must Be Moved to Comply with WGS-84 Datum November 8, 2001 Geodesy In Aviation Slide No. 16
P S O M A S Effect of Datum on Aviation Effect of Datum on Aviation Since 1985 40% of all Since 1985 40% of all Where the end Aviation Fatalities Have Aviation Fatalities Have of the runway Resulted from Resulted from is located Controlled Flight Into Controlled Flight Into AFTER WGS-84 Terrain. Terrain. Survey 36 Philip M. Condit Philip M. Condit Chairman-CEO, Boeing Corp . Chairman-CEO, Boeing Corp . Where the aircraft is at the end of the GPS approach procedure 462 m using WGS-84 Datum The Position of the Runway Now Conforms to WGS-84 November 8, 2001 Geodesy In Aviation Slide No. 17
P S O M A S Heights Heights � Present a Major Problem for Global � Present a Major Problem for Global Navigation Navigation � Where I s Height (Elevation) � Where I s Height (Elevation) Measured From? Measured From? � Center of the Earth � Center of the Earth � Surface of the Earth � Surface of the Earth � Somewhere Else? � Somewhere Else? � Where is Mean Sea Level (MSL)? � Where is Mean Sea Level (MSL)? November 8, 2001 Geodesy In Aviation Slide No. 18
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